In a gas operated automatic or semi-automatic firearm, propulsion gases are ported from the bore of the barrel, through a gas block, and into a gas tube, which carries the gases rearwardly for either direct impingement or gas piston operation to cycle the firearm's action. In the case of a typical AR15-type firearm, or the select-fire M16/M4 counterparts, the gas tube connects the gas block with the gas key on the bolt carrier for direct impingement cycling of the bolt carrier group. The burning propulsion gases carry a substantial amount of heat energy, some of which is transferred to the gas tube, which is typically made of stainless steel. When rounds are fired in a slow sequence, heat transferred to the gas tube will typically dissipate before reaching a level that could cause failure. However, rapid fire of one hundred or more rounds can result in a significant amount of heat being built up in the gas tube. If the temperature of the metallic gas tube exceeds a critical point, or after the firearm has been put through many cycles of overheating and cooling, the metal can become weakened and unable to contain the gas pressure. A “blowout” failure of the gas tube will render the firearm inoperable.
Various solutions have been proposed to address this problem, ranging from simply thickening the walls of the gas tube to adding fins or other structure that will increase heat dissipation from the gas tube. Each of these have a significant increase in cost, increased weight, or requiring a specially sized and shaped device to fit each of a wide range of gas tube shapes and lengths. Even in otherwise “identical” gas tubes, there is typically some variance in the required bend due to the method of manufacturing.